3v4l.org

run code in 300+ PHP versions simultaneously
<?php function &g(&$v) { return $v; } function f(&$v) { $v = 5; } $foo = null; $name = 'foo'; call_user_func_array('f', array($a = &g($$name))); //var_dump(array(g($$name))); var_dump($foo);
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Warning: f(): Argument #1 ($v) must be passed by reference, value given in /in/ftjlX on line 12 NULL
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33
Warning: Parameter 1 to f() expected to be a reference, value given in /in/ftjlX on line 12 NULL
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28
NULL
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228.28 ms | 404 KiB | 328 Q